In the oil and gas industry many wellbore operations rely on the ability to move or shift certain downhole components. Such shifting may be achieved by use of shifting tools, which are typically deployed and manipulated from surface.
For example, components, such as sleeves, may require to be shifted for a variety of reasons, such as to actuate slips, set packers, open one or more ports, or the like.
Also, in some circumstances it may be necessary to shift a downhole component from an active to a redundant position, or vice versa. For example, a ball seat may be initially installed in a configuration in which a ball travelling downhole may be caught, for example to initiate an actuation event, to move the ball seat, to create a plug or flow diversion, or the like. In some cases an operator may decide that the function of the ball seat is no longer required, and thus may take positive steps to move the ball seat to a position where the seat no longer functions.
WO 2011/117601 and WO 2011/117602 each disclose a mechanical counting device which is mounted within a housing and is configured to be acted upon by a number of passing balls dropped from surface to linearly progress the device along the housing in a corresponding number of discrete steps until reaching an actuation site, whereupon an associated tool is actuated. UK patent application 1223191.6 also discloses a mechanical counting device, or indexing sleeve, which is acted upon by a number of passing balls to move in corresponding discrete steps. UK 1223191.6 discloses the ability to move the indexing sleeve with a shifting tool to a redundant position such that passing balls to not cause any movement thereof, thus preventing an associated tool from being actuated.